Flywheel



March 26, 1929- G. w. PANGBURN FLYWHEEL 511e@ May 2. 1927 Fig 5 PatentedMar. 26,1929. y

^ UNITED lsrA'rEs PATENT OFFICE.

Application filed lay 2,

This invention relates toflywheels adapted to Vsteady the rotation of ashaft. The object of my invention is to increase the pickup of theengine. I attain this object by pro- `viding a flywheel having avariable distribution of weights and therefore a variable moment ofinertia, increasing with an-1ncrease in therate of rotation, whereby theenergy absorbed b the flywheel is proportionately less when t eengine-is rotating slowly than ywhen it is'turnin'g at a higher speed;so that a sudden increase in the torque of the engine shaft produces a-higher'increase in the rate of rotation thereof than the same increasein torque would with a flywheel offixed greater moment of inertia.

I attain this and other objects by the devices, mechanisms, andarrangements, illusti'ated` in the. accompanying drawings, in

dltlons I have lnvented the following lde which Fig. 1 is a verticalsection of my improved ywheel-taken on the line 1 l 1n Fig. 2; Fig. 2 isan end elevation the`1gof, a

portion thereof being brok'en away; and Fig.

3 is a plan view of a ortion thereof. n

Similar numerals o reference refer to s 1m1, lar. parts throughout theseveral views.

lt is a well-known fact that .the effect of a flywheel is notproportionate to its weight but to the distribution of. its weightinrelation to the center of rotation. This effect -is determined by afactor known as the moment of inertia of the ,axial section through 'theflywheel and by the area of the said section. The weightof the flywheelvaries, of course, directly with the area of the section but the momentof inertia depends on the distribution of the weightin relation to thecenter of rotation of the iiywhe'el. The moment of inertia of theflywheel is the sum of the products of the weight of each particle inthe flywheel multiplied by the square of its distance from the centerof'rotation. Therefore the moment of inertia of a body Whose greatestconcentration of material is near the center of rotation is very muchless than that of a body of equal weight whose material is concentratedfurther from the said'centen Whenanengine is'jrunning slowly and it isdesired .to suddenlyfehange its rate to a high speed, then the amountofenergy which is absorbed by the' iywheel by the sudden change depends onthe moment of inertia of the iiywheel and if this is small then vtheincrease `in speed is correspondingly rapid, but if the moment ofinertia is largethe increase of speed is small, and the energy absorbedby ma?.` serial No. 188,221.

the flywheel is correspondingly large. It is I desirable in themechanical operation, especi'- ally Kof gasoline engines and moreespecially .in automobiles, to provide a flywheel which will efe'ctivelsteady the rotation of the shaftby absor ing the high forces at the timeof each ex losion and returning the energy" to the sha t at intermediatepoints. A iiy.- `wheel designed to accomplish this effect and to producesmooth running when` the engine is runningfat its normal economic speedhas .too large almoment of inertia to permit any sudden change from alow idling speedto a h igh working speed. Also, a flywheel deslgned topermit this sudden pickup of speed would have a moment of inertia toosmall to cause the engine to run smoothly when doing its full wor f Inorder to combine these two opposite v*conmounted in asuitable bearing 2and is pro- A vided with a flywheel attached thereto. lThis* iywheel isprovided with a central boss 3 and with a disk 4 extending outwardtherefrom. The disk 4 may conveniently be rovided with gear teeth 5`onits outer perip ery for the purpose of gearing with the -usual startermechanism whereby the engine is started. The ring which usuallyforms themain weight of the flywheel is located as far as possible from thecenter of the shaft` and is, in my invention, substltuted by a series oflugs 6 extending laterally from the said disk 4 at uniform distancesapart and of uniform size and shape. The inner portions of all f centlugs 6 I mount a movable weight 9 having guide lugs 10 which enter thesaid grooves 8l in the sides of the said lugs 6. Each of these movableweights 9 is free'to move outward between the said lugs, under theaction of the centrifugal force -thereon when the Hywheel is rotated,and this outward motion is resisted by the following describedmechanism. Each weight 9 is provided with an inward extending shank 11which passes through the flange 7 towards thecenter of the shaft. A link12 is pivotally attached to the end of the said shank 11 and connects itto the end of the long arm 13 of a bell-crank lever. The bellcrank leveris pivoted at 14 between two lugs 15 extending from the disk 4 of theflywheel. The short arm 16, of the bell-crank lever, extends inwardtoward the shaft and engages the front surface of a disk 17. The disk 17is loosely mounted on the boss 3 and is free to move axially thereon. Aflange 18 is adjustably secured to the end of the boss 3 and extendsoutward therefrom. A helical spring 19 is coiled around the boss 3between the flange 18 and the disk 17 and presses the said disk awayfrom the said flange. Telescoping Hanges 20 may be formed on the disk 17and on the Harige 18 to form a box adapted to enclose the said spring.

lll`hus it will be seen that the spring 19 `Ipushes the disk 17 againstall of the short arms 16 of all the bell-crank levers to turn them ontheir pivots 14 andto draw all of the weights 9 inward toward the centerof the flywheel. As the flywheel rotates, the centrifugal force appliedto all of the said moving weights 9 tend to force them outward betweenthe lugs 6 and against the action of the said spring 19, until the sumof all the centrifugal forces is balanced by `gxli resistance of thecompressed spring 19. en the said moving weights 9 are in theirinnermost positions, the moment of inertia of the wheel is less thanwhen they are at their outermost position. The energy necessary forturning the engine at a slow speed is therefore less than if the weights9 were in their outermost positions. s'the speed of the flywheelincreases the moment of inertia thereof increases because the weights 9move outward thereon.

Having therefore described my invention what I claim is v 1. Anautomatically variable flywheel, comprising amain rotating wheel, havingan enlarged rim; a series of recesses formed in the outer periphery ofsaid riln, the central line of each. recess being radial from the centerof said wheel and the sides being parallel with said central lines;weights mounted in said recesses, each said Weight being of less depththan the recess in which it fits and being free to move outwardly insaid recess under the action of centrifugal force; and resilientrestraining means engaging all said lweights equally and adapted tooppose the outward movement thereof.

2. An automatlcally variable flywheel, comprising a mam rotatingwheel,hav1ng an Aenlarged rim; a series of recesses formed in 'theaction of centrifugal force; guide lugs formed on said weights andextending therefrom to engage in said guide grooves whereby the weightsare guided in said recesses; and resilient restraining means engagingall said weights equally and adapted to oppose the outward movementthereof.`

3. An automatically variable compound flywheel, comprising a mainrotating wheel, having an enlarged rim, said main wheel having a fixedmomentof inertia; recesses formed in said rim, thereby reducing thenormal moment of inertia of said wheel; weights mounted in each saidrecess and outwardly slidable thereinunder the action of centrifugalforce thereon, said weights together partially restoring the moment ofinertia of the complete wheel when they are positioned at the inner endsof said recesses and increasingly restoring the moment of inertia of thecomplete wheel as they moved outward towards their outermost positions;and a single resilient means engaging all said weights throughintermediate mechanism and opposing equally their outward movement insaid recesses, whereby the `combined moment of inertia of the completewheel is less than it is rotated slowly than when it has attained a.

normal rate of rotation and whereby its resistance to a change in therate of rotation is proportionately less when rotating slowly than whenrotated at normal speed.

GEORGE l/V. PANGBURN.

